Problem: $ { \left[\begin{array}{rr}{-1} & {-1} \\ {3} & {3}\end{array}\right]-\left[\begin{array}{rr}{-1} & {1} \\ {3} & {3}\end{array}\right] = {?} } $
To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}-{-1} & {-1}-{1} \\ {3}-{3} & {3}-{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {-2} \\ {0} & {0}\end{array}\right]}$